mfencedBseparators8

W3C sample	WIRIS
	$\left(a_1,a_2,a_3\right)$

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mfenced>
    <msub>
      <mi>a</mi>
      <mn>1</mn>
    </msub>
    <msub>
      <mi>a</mi>
      <mn>2</mn>
    </msub>
    <msub>
      <mi>a</mi>
      <mn>3</mn>
    </msub>
  </mfenced>
</math>

Author: Robert Miner and Jeff Schaefer, Geometry Technologies